Effects of extracellular sodium on μ-opioid receptors coupled to potassium channels coexpressed in Xenopus oocytes

摘要: Wild-type or mutant H297N H297Q of the mu-opioid receptor were co-expressed with inwardly rectifying potassium channel GIRK1 in oocytes from Xenopus laevis. Under voltage clamp, pairs concentration response curves generated using agonist normorphine a bathing medium containing 38.5 mM sodium an identical which was replaced by equimolar choline. The maximum currents greater presence about 30% at wild-type receptors and 100% receptors. EC(50) values tended to increase somewhat as well, though these differences reached statistical significance only for H297Q. Flame photometry detected no change intracellular concentrations oocytes, suggesting that effect solely extracellular. Thus sodium, long known its effects on vitro ligand binding receptors, also affects overall transduction revealed oocyte model complete, living cell system.